1. Field of the Invention
The present invention relates to an electromagnet assembly for use in an electromagnetic apparatus, such as an electromagnetic clutch for use in controlling the transmission of power from an automobile engine to a refrigerant compressor in an automobile air conditioning system. More particularly, it relates to a connecting structure between a connector and a ring case in the electromagnet assembly.
2. Description of Related Art
Referring to FIG. 1, an electromagnet assembly 7, which comprises a ring member 1, a coil bobbin 3, and a ring case 4, is known in the art. Ring member 1 has a toroidal shape having a spool portion, which has an exterior open edge. Coil bobbin 3 has ring member 1 and an electrical wire 2, which is wound around the spool portion of ring member 1. Ring case 4 has an annular groove, an open edge of which is in a direction parallel to its axis. Coil bobbin 3 is inserted into the annular groove of ring case 4. An opening 4a is formed through ring case 4 adjacent to its closed end surface. A connector 5 is disposed on ring case 4 adjacent to its closed end surface and covers opening 4a. A first end 2a and a second end 2b of electrical wire 2 and a first lead 6a and a second lead 6b, which extend to the external electric circuit, are joined, respectively in connector 5. Electromagnet assembly 7, for example, is used in an electromagnetic clutch 9 of a compressor 8 in an automobile air conditioning system, as shown in FIG. 2. Electromagnet assembly 7 engages compressor 8 through a ring-shaped plate 10, which is affixed to the closed end surface of ring case 4.
Referring to FIGS. 3-6, the connecting structure between connector 5 and ring case 4 and the wiring connecting structure in connector 5 are shown. As shown in FIGS. 3 and 4, connector 5 has a case 5a having a box shape including a bottom, and cap 5b, which closes an open end of case 5a. Case 5a is fixed to ring case 4 by a pair of first hooks 10a formed on ring shaped plate 10 which engage a pair of first receiving portions 5a1 formed on case 5a. In an engaging process, first hooks 10a are formed by bending straight portions to engage first receiving portions 5a1. Cap 5b is fixed to case 5a by engaging a plurality of second receiving portions 5a2 formed at case 5a with a plurality of hooks 5b1 formed at cap 5b. A projection portion 5a3, which is formed on case 5a, is inserted into opening 4a. An O-ring 11, which is disposed in an annular groove formed on case 5a, surrounds opening 4a and abuts the closed end surface of ring case 4.
As shown in FIGS. 4-6, first end 2a and second end 2b of electrical wire 2 are introduced into opening 4a through holes 1a and 1b formed on an end surface of ring member 1 and are extended into connector 5 through a pair of penetrating holes 5a4, which are formed through projection portion 5a3. A contact 12 having a first electric connection is connected to an end of second lead 6b, which is inserted into connector 5. In addition, contact 12 having a second electric connection is connected to an end of first lead 6a, which is inserted into connector 5. First end 2a of electrical wire 2 is disposed between a first receiving portion formed at case 5a of connector 5 and a second receiving portion formed at contact 12, which is connected to first lead 6a. Second end 2b of electrical wire 2 is disposed between a third receiving portion formed at case 5a of connector 5 and a fourth receiving portion formed at contact 12, which is connected to second lead 6b. Thus, first end 2a and second end 2b of electrical wire 2 are connected to first lead 6a and second lead 6b, respectively.
Coil bobbin 3 is fixed to ring case 4 by a resin 13 (e.g., epoxy resin) which is poured into ring case 4 from an open end of the annular groove of ring case 4. O-ring 11, which is disposed between case 5a and the closed end of ring case 4, prevents resin 13 from leaking to the outside of the closed end surface of ring case 4 through the gap between projection portion 5a3 of case 5a and a surrounding wall of opening 4a, when resin 13 is poured into ring case 4.
In the known electromagnet assembly 7 for use in an electromagnetic apparatus, it is necessary to secure first hooks 10a to ring-shaped plate 10 and to equip O-ring 11 when connector 5 is fixed to ring case 4. As a result, the efficiency during manufacturing of fixing connector 5 to ring case 4 may be reduced.